Foam delivery system

ABSTRACT

A foam delivery system comprises two delivery tubes providing a mixing chamber with a two-part polymeric foam. The mixing chamber mixes the two-part polymeric foam below a ground surface. A delivery manifold with delivery arms discharges the two-part polymer resin from the foam delivery system. A method of distributing a foam delivery systems comprises lowering a foam delivery system below a ground surface and discharging a polymer resin into the ground surface from a mixing chamber located below the ground surface. The mixing chamber discharges the polymer resin while the mixing chamber is lifted towards the ground surface, providing an expanding base of polymer resin. In that the chemicals are mixed at depth, that is, at the depth of the desired injection points, the possibility of premature setting and plugging of the delivery system is negated. An injector, comprising the mixing chamber and the delivery manifold, mixes the two-part chemical system at depth and then simultaneously distributes the mixed chemicals to up to six injection points at any desired depth.

BACKGROUND

This patent document relates to a system to deliver two-part expanding polymeric resins to below surface depths.

In a typical two-part expanding polymeric resin system, the two chemical components are impingement-mixed at the surface through appropriate pumping/proportioner equipment and delivered through a single injection tube or probe. The depth to which the mixed components can be delivered is limited to: (a) the time it takes the mixed components to gel and “set-up” which is a function of the density/mix of the resin system and the temperature the resin is injected; (b) the back-pressure created at the end of the probe due to the expansion of the resin after it is injected; (c) if air-locks within the delivery probe occur; and (d) the pressures the mixed material can be injected through a single probe.

The gel time of typical two-part expanding resin systems is generally very short and usually measured in seconds. The more reactive or faster is the expansion of the resin system, the quicker the gel time or set-up time. Similarly, within limits, as the temperature of the chemicals increase, the gel time or set-up time decreases. The gel time or set-up time often limits the depths to which an already-mixed polymeric resin system can be delivered before the material “sets up” and plugs the injection probe.

Once the mixed expanding resin is injected through the injection probe, a back-pressure often develops around the base of the area of the injection and the back-pressure slows down the rate of injection of the mixed resin, which causes the resin to prematurely set-up in the injection probe and plugs the probe.

If the soils at depth into which the expanding resin system is being injected into are very cohesive or saturated, the air within the injection probe could create an air-lock as the chemicals are being delivered from the surface through a single injection probe. At the very least, the back pressure caused by the air within the injection probe will slow the progress of the mixed two-part resin system and therefore minimize the amount of material that can be injected before the expanding resin system sets-up and plugs the probe.

There is a direct relationship between the pressure at which the mixed resins are injected and the depth to which the resins can be delivered. The higher the pressure the faster the material can be delivered through a single injection probe and therefore the deeper and the longer the material can be delivered before the resin sets-up and plugs the injection probe. Despite applied pressures in delivering the two-part resin through a single probe, eventually the probe will plug due to depth and/or back-pressure.

SUMMARY

This patent document addresses these and other difficulties with the prior art.

In an embodiment there is a method of delivering a polymer resin below ground surface. A bore that is accessible from the ground surface is created below the ground surface. A mixing chamber, which is a component of a foam delivery system, is lowered into the bore. A polymer resin is discharged from the mixing chamber of the foam delivery system into the bore. The mixing chamber is lifted within the bore and the polymer resin is discharged from the foam delivery system when the foam delivery system is lifted within the bore.

In an embodiment there is a foam delivery system for delivering an expanding polymer resin below a ground surface. The foam delivery system has a first delivery tube having a surface end and a mixing end and a second delivery tube having a surface end and a mixing end. A mixing chamber is attached to the respective mixing ends of each of the first and second delivery tubes. A first delivery arm and a second delivery arm provide a pathway from and connect to the mixing chamber for discharging the expanding polymeric resin from the mixing chamber.

In an embodiment there is a method of delivering an expanding polymer resin having a first component and a second component. An injector, which comprises a mixing chamber, is placed at a first sub-surface location. The first component and the second component of the expanding polymer resin are mixed in the mixing chamber to create a mixed polymer resin. The mixed polymer resin is discharged from the injector at the first sub-surface location creating a first foam discharge. The injector is moved to a different sub-surface location. The first component and the second component of the expanding polymer resin are mixed in the mixing chamber when the injector is at the different sub-surface location to create the mixed polymer resin. The mixed polymer resin is discharged from the injector at the different sub-surface location creating a second foam discharge, which expands into contact with the first foam discharge.

These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:

FIG. 1 is a partial section view of a foam delivery system in a screw pile;

FIG. 2 is a partial section view of a foam delivery system in a first sub-surface location in a bore; and

FIG. 3 is a partial section view of a foam delivery system in a second sub-surface location in a bore.

DETAILED DESCRIPTION

In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite article “a” before a claim feature does not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

FIGS. 1-3 show embodiments of a foam delivery system 10. The foam delivery system 10 has a first delivery tube 12 and a second delivery tube 14 each having a surface end 30 and a mixing end 32. An injector 16 comprising a mixing chamber 22 is attached to the respective mixing ends 32 of each of the first and second delivery tubes 12, 14. A delivery manifold 24 comprising first and second delivery arms 52 connects to the mixing chamber 22 and provides a pathway for discharging the expanding polymeric resin from the mixing chamber 22. Air bleed valves 20 connect to the mixing ends 32 of the first and second delivery tubes 12, 14. The air bleed valves 20 are hard fixed into each of the first and second delivery tubes 12, 14 thereby preventing the possibility of air locks as the two components Component “A” and Component “B” are pumped through the delivery tubes 12, 14 to depth.

FIGS. 2 and 3 show an embodiment of the foam delivery system 10 in operation. The foam delivery system 10 delivers an expanding polymer resin having a first component (Component “A”) and a second component (Component “B”) into a sub-surface location through the first and second delivery tubes 12 and 14, respectively. The injector 16 is placed at a first sub-surface location, for example the position shown in FIG. 2. The first component and the second component of an expanding polymer resin are transported through the first and second delivery tubes 12, 14 to the mixing chamber 22 to create a mixed polymer resin 38. The mixed polymer resin 38 is discharged from the injector 16 at the first sub-surface location to create a first foam discharge 40. The injector 16 is moved to a different sub-surface location as shown in FIG. 3. Again, the first and second components of the expanding polymer resin are mixed in the mixing chamber 22 when the injector 16 is at the different sub-surface location to create the mixed polymer resin. The mixed polymer resin is discharged from the injector 16 at the different sub-surface location creating a second foam discharge 42 so that the second foam discharge 42 expands into contact with the first foam discharge 40 as shown in FIG. 3.

To deliver foam below a ground surface 34 a bore 36 (FIG. 2) may be created below the ground surface 34 prior to operation of the foam delivery system 10. In the embodiment of FIG. 1, the foam delivery system 10 lies within a screw pile having a drill stem wall 18 and a screw 28 at the base to bore into the ground. As shown in FIG. 2, the bore 36 is accessible from the ground surface 34. In the embodiment of FIG. 2 the mixing chamber 22 is lowered into the bore 36. A polymer resin is discharged from the mixing chamber 22 of the foam delivery system 10 into the bore 36. The foam mixing chamber 22 is lifted within the bore 36. The polymer resin is discharged from the foam delivery system 10 when the foam delivery system 10 is lifted within the bore 36. For example, the foam delivery system 10 may continuously discharge the polymer resin as the foam delivery system 10 is lifted in the bore 36.

FIG. 1 shows an embodiment in which the pile stem 44 containing the foam delivery system 10 is a drill stem that can be driven, screwed or drilled to the desired depth. Component “A” and Component “B” are independently pumped in the desired proportions through delivery tubes 12, 14 to the depth that the mixed polymer resin is to be injected. The polymer resin is injected to the exterior of the drill stem wall 18. Below the air bleed valves 20 are a mixing chamber 22 and delivery manifold 24 which together comprise the injector 16, or mixing/manifold delivery module. The delivery arms 52 of the delivery manifold 24 attach to a connecting tube 50 that attaches between a port 46 of the delivery arm 52 and a stem wall port 48 in the drill stem wall 18. The stem wall ports 48 in the drill stem wall 18 may be pre-attached to the connecting tubes 50 prior to being lowered into the ground. The air bleed valves 20 are each appropriately-sized conventional air bleed valves and are affixed to each of the delivery tubes 12, 14 to evacuate air from the delivery tubes 12, 14 as the two liquids, Components “A” and “B”, are being pumped into the delivery tubes 12, 14.

Below the mixing end 32 of the delivery tubes 12, 14, the two Components “A” and “B” combine together in the mixing chamber 22. The mixing chamber 22 comprises off-setting arms 26, which may be appropriately angled and spiraled to effect maximum mixing of the two chemicals coupled with opposing flow of the chemicals themselves.

In other embodiments, the pile stem may be a different form of hollow pipe. For example, the pile stem may be a drill stem or a conduit

In other embodiment other expandable synthetic substances having similar properties may be used. The particular resin system used can be tailored to meet specific design applications relating to compressive strength, tensile strength, shear strength, flexural strength and other structural characteristics to meet the specific design application of the resin system for any given project. In some embodiments, for example, the polymeric resin system to be delivered at depth may be a high density, two-part, closed-cell, hydro-insensitive polymer resin, such as a polyurethane system.

In some embodiments, the delivery tubes or probes can be made of metal such as aluminum, copper, steel or other metal or, made of a synthetic material such as rigid or flexible plastics, fiberglass or other synthetic material. The delivery tubes 12, 14 could be sectional with each section being welded, friction fitted, glued, screwed or joined together in some other fashion. The embodiments of FIGS. 1 to 3 show schematic designs of the foam delivery system 10. In other embodiments, various orientations and shapes of the components of the foam delivery system are possible.

In some embodiments, the delivery tubes 12 and 14 can be, for example made of rigid metal, synthetic material or flexible metal through which each of the two component parts of the expanding resin will be individually pumped to the desired depth. The delivery tubes 12 and 14, which for example, may have a ¼″-¾″ inside diameter or larger, may be constructed from one continuous length or may be sectional and glued, welded, screwed, friction fit, or otherwise fit together to form a delivery tube of the desired length. The pumping system(s) may be, for example, a conventional pumping and/or proportioner equipment readily available in the marketplace capable of pumping the two components in their proper proportions into the delivery system described in this Patent document.

The foam delivery system 10 may be used in a variety of applications, for example for stabilizing and/or densifying base soils at extreme depths, for stabilizing around the base of screw-piles and other types of piles that have been screwed or placed at depth, for densifying base soils in earth quake prone zones as a prevention against liquefaction, for filling voids along vertical planes at depth in such cases as for example old mine tunnels and shafts, new mining tunnels and shafts, conduits, or any other structure resting along a vertical plane that requires back-filling and stabilization and for filling voids along horizontal planes in such cases as for example abandoned conduit, culverts, mined tunnels, or any other structure resting along a horizontal plane that requires void-filling.

Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. 

1. A method of delivering an expanding polymer resin having a first component and a second component comprising the steps of: placing an injector at a first sub-surface location, the injector comprising a mixing chamber; mixing the first component and the second component of the expanding polymer resin in the mixing chamber to create a mixed polymer resin; discharging the mixed polymer resin from the injector at the first sub-surface location creating a first foam discharge; moving the injector to a different sub-surface location; mixing the first component and the second component of the expanding polymer resin in the mixing chamber when the injector is at the different sub-surface location to create the mixed polymer resin; and discharging the mixed polymer resin from the injector at the different sub-surface location creating a second foam discharge, the second foam discharge expanding into contact with the first foam discharge.
 2. The method of delivering an expanding polymer resin of claim 1 in which the injector discharges the mixed polymer resin continuously as the injector is moved to the different sub-surface location.
 3. The method of delivering an expanding polymer resin of claim 2 in which the different sub-surface location is vertically higher than the first sub-surface location.
 4. The method of delivering an expanding polymer resin of claim 1 further comprising the steps of drilling a borehole into the ground before the step of placing the injector attached to a mixing chamber at a sub-surface location and in which the first sub-surface location and the different sub-surface location lie within the borehole.
 5. The method of delivering an expanding polymer resin of claim 1 in which the expanding polymer resin is polyurethane.
 6. A foam delivery system for delivering an expanding polymer resin comprising below a ground surface: a first delivery tube having a surface end and a mixing end and a second delivery tube having a surface end and a mixing end; a mixing chamber attached to the respective mixing ends of each of the first and second delivery tubes; and at least a first delivery arm and a second delivery arm connecting to the mixing chamber, the first delivery arm and the second delivery arm providing a pathway for discharging the expanding polymeric resin from the mixing chamber.
 7. The foam delivery system of claim 6 in which each of the first and second injectors define a discharge direction for discharging the polymeric resin from the mixing chamber, and in which the discharge direction of the first injector is not aligned with the discharge direction of the second injector.
 8. The foam delivery system of claim 6 in which a bleed valve is attached to the first delivery tube and the second delivery tube above the mixing chamber.
 9. The foam delivery system of claim 6 further comprising a drill stem encasing all of the first delivery tube, the second delivery tube, the mixing chamber, the first injector and the second injector.
 10. The foam delivery system of claim 9 in which the drill stem is a screw pile.
 11. A method of delivering a polymer resin below ground surface comprising the steps of: creating a bore below the ground surface, the bore being accessible from the ground surface; lowering a mixing chamber into the bore, the mixing chamber being a component of a foam delivery system; discharging a polymer resin from the mixing chamber of the foam delivery system into the bore; lifting the mixing chamber within the bore; and further discharging polymer resin from the mixing chamber of the foam delivery system after lifting the mixing chamber within the bore.
 12. The method of delivering a polymer resin below ground surface of claim 11 in which the polymer resin is discharged continuously from the foam delivery system as the foam delivery system is lifted within the bore.
 13. The method of delivering a polymer resin below ground surface of claim 11 in which the polymer resin is discharged in discrete steps from the foam delivery system as the foam delivery system is lifted within the bore.
 14. The method of delivering a polymer resin below ground surface of claim 11 in which the step of creating a bore below surface and being accessible from the ground surface is performed by the foam delivery system.
 15. The method of delivering a polymer resin below ground surface of claim 11 further comprising the step of releasing excess air from the foam delivery system prior to the step of discharging a polymer resin from the foam delivery system. 